1. Field of the Invention
The present invention relates to a thin film transistor device and a manufacturing method thereof, and more particularly, to a thin film transistor device including a low resistance doped layer formed by a non-implant process and a laser treatment, and a manufacturing method thereof.
2. Description of the Prior Art
Electrical mobility of polysilicon is higher than electrical mobility of amorphous silicon, and performance of polysilicon thin film transistors (TFTs) is generally better than performance of amorphous silicon thin film transistors, which are widely used in TFT-LCD. Related technologies of low temperature polysilicon (LTPS) have been continuously improving, and major problems such as bad film uniformity over large substrate have been gradually ameliorated. Therefore, the LTPS process is also developed for being applied to large substrates. In the conventional LTPS process, a doped layer, which is employed for lowering the contact resistance in the thin film transistor, is generally formed by an ion implant process. In addition to some related technical issues to be solved, the cost of the ion implant machine for large substrate may also be a big problem. Therefore, other approaches for forming the doped layer with low resistance are under development in the related industries.
Additionally, because a N type TFT or a P type TFT may be obtained by combining the polysilicon with different conductivity type doped layers, the LTPS process may generally be employed for forming the N type TFT and the P type TFT on the same substrate. In the conventional LTPS process, a patterned N type doped layer and a patterned P type doped layer are formed on a same surface. Additional processes are required for avoiding interfering with each other when forming the patterned N type doped layer and the patterned P type doped layer. Process may then become more complex, and related cost may increase too.